Bump Polly from 8.6.5 to 8.6.6 (#45)

---
updated-dependencies:
- dependency-name: Polly
  dependency-version: 8.6.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]

MailAgent/MailAgent.csproj

@@ -57,7 +57,7 @@
     <PackageReference Include="Microsoft.Extensions.Options" Version="10.0.0" />
     <PackageReference Include="MimeKit" Version="4.15.1" />
     <PackageReference Include="Nito.AsyncEx" Version="5.1.2" />
-    <PackageReference Include="Polly" Version="8.6.5" />
+    <PackageReference Include="Polly" Version="8.6.6" />
     <PackageReference Include="Polly.Extensions.Http" Version="3.0.0" />
     <PackageReference Include="Serilog" Version="4.3.0" />
     <PackageReference Include="Serilog.Exceptions" Version="8.4.0" />